Fabric or gauze of uniformly oxidized cellulose



y 1947- w. o. KENYON ETAL 4 2, 23,707

FABRIC 0R GAUZE OF UNIFQRMLY OXIDIZED CELLULOSE Filed March 2, 1945 FIG. I.

FIG. 2.

WILLIAM o. KENYON CORNELIUS C.UNRUH INVENTORS Patented July 8, 1947 FABRIC OR GAUZE OF UNIFORMLY OXIDIZED CELLULOSE William 0. Kenyon and Cornelius C. Unruh, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application March 2, 1945, Serial No. 580,734 6 Claims. (Cl. 139-426) This invention'relates to fabric or gauze of uniformly oxidized cellulose fibers, such as cotton, viscose, flax, or other relatively pure or purified forms of cellulose fibers, and the method of preparing such material which involves first oxidizing the cellulose fibers in staple form with N02 and then spinning and weaving the so oxidized cellulose to prepare the fabric therefrom. When N02 (nitrogen dioxide) is referred to herein, it is intended that the term shall include the dimer N204.

In the treatment of wounds, cuts and the like, it is customary to use a, cotton sponge or gauze packing to aid in checking the flow of blood and to afford protection for the wound. After the flow of blood has been stopped and clotting and healing has commenced, it is necessary to ultimately remove the sponge or gauze but such removal may rupture or pull off the scab, cause renewed bleeding, interrupt the healing process, or may introduce new infection and generally speaking is very unsatisfactory.

In the case of the surgery in the interior of the body, profuse bleeding sometimes occurs and while it is possible for a surgeon to tie oif the'larger blood vessels, there are many conditions where oozing of blood from the small capillaries continues and these areas must be heavily packed with gauze in an effort to stop the flow of blood. This has been unsatisfactory for two reasons-(l) the gauze acts as a foreign body to the tissues and marked irritation usually results, and (2) even if healing does progress, the gauze must eventually be removed, whereupon the healing process is interrupted and renewed bleeding and possible new infection may result. This is particularly true where incisions are made in such organs as the kidneys, liver, lungs, and brain, which organs are permeated with small capillaries andin which hemostasis is extremely difilcult.

It has been discovered that when cotton or other cellulose is sufiiciently oxidized with N02, i. e. to a point of solubility in 2% aqueous alkali and preferably to a point of solubility in 0.15 molar solution of sodium bicarbonate, such cellulose not only retains substantiallyits-original physical form but is soluble in and absorbable .by human body fluids within a matter of a relatively short time; in addition, such oxidation imparts to the cellulose a very marked hemostatic effect. Accordingly, when a packing of this oxidized cellulose is inserted within the body tissues, the incision may be closed up, the oxidized cellulose will be readily gelatinized by the body fiuidsand within a few days it will be found that the cellulose has been completely absorbed. Thus, the oxidized cellulose stops the flow of blood quite promptly, the healing process commences almost immediately and such healing is never inter rupted by any necessity to remove the packing.

While oxidation of the cellulose to a range of between 13% and 20% total carboxyl in the cellulose and preferably from 15% to 18% carboxyl has been found to be the desirable range for complete absorption of the oxidized cellulose by the body fiuids, there is great utility in surgery for cellulose which has been oxidized to a lower degree such, for instance, as from 5% to 9%. Within this 5% to 9% range the oxidized cellulose will not be absorbed by the body fluids but will gelatinize in the body fluids to a suflicient extent so that when placed upon an open wound, such as a burn or bad abrasion or an open cut, the oxidized cellulose gelatinizes to a sutlicient extent that a rather slippery gelatinous surface forms upon the cellulose packing next to the wound such that it will not adhere to the wound; thus, when such oxidized cellulose is used as an outer dressing, the healing process can take place and the dressing be removed without rupturing any scab formation and a new dressing applied as frequently as necessary or desired.

Heretofore it has been customary to oxidize such cellulose in gauze form inasmuch as that is the form in which surgical packings are normally made and used. However, one diiliculty has been encountered with such procedure in that the twisted threads from which such gauze is woven are not uniformly oxidized, the outer fibers of the threads being oxidized to the desired extent but the inner fibers of the threads being underoxidized for the desired purpose. It will be apparent that when such gauze is used as a' packing for inner incisions (called buried use) the presence of any fibers which are not oxidized to the extent necessary to give solubility in or absorption by body fluids will act as foreign bodies and are therefore undesirable. The same objections are true to a lesser extent where the gauze is employed for external surgery in that fibers which are oxidized to a lesser degree than that contemplated for the particular use, will not gelatinize to the extent of the regular fibers and will adhere to scab formations and when removed will interrupt the healing process.

Thus far it has been attempted to overcome such lack of uniformity in oxidation by obtaining a high enough average carboxyl in the gauze so that all fibers will be oxidized to a minimum trogen tetroxide, for

, treatment of the-cellulose which, for instance, for buried use, will exceed 13% carboxyl. This, however, means that many of the fibers are oxidized beyond the desirable point and not only become friable, lose their tensile strength and shrink badly, but their ability to resist long time keeping is impaired. Accordingly, it will be apparent that a gauze in which all the fibers are substantially uniformly oxidized is most desirable for either the buried use or the external use.

We have found that surgical gauze or other surgical fabrics in which the cellulose is uniformly oxidized may be produced by first oxidizing the cellulose, such as purified cotton, in loose wellflufied form, washing it free from reaction prod ucts, spinning it into thread and then weaving it into gauze or other surgical fabric, which is eminently suitable for surgical purposes, such as the checking of bleeding without sticking or adhering to the tissues.

It is, therefore, an object of our invention to provide fabric of uniformly oxidized cellulose fibers so as to out having therein any material which either is not oxidized, is not oxidized to a degree necessary for the purpose at hand, or is over-oxidized with the accompanying poor keeping qualities. Another object of our invention is=to provide a method of making textile materials of oxidized cellulose fibers in which any appreciable shrink age is avoided and the product obtained has sub.- stantially the desired dimensions initially and throughout its use. A' further object of our invention is to avoid the dangerof uneven shrinkage which is often met with in the use of cotton in fabric or thread form as the starting material for the preparation of oxidized cellulose.

Our invention may as follows:

Purified staple cotton, viscose staple, purified fiax fibers or other relatively .pure or purified cellulose fiber which had. been loosened such as by picking and combing, in air-dry condition, such as containing from to 6% moisture, is subjected to the action of nitrogen dioxide or its dimer, ni-

a period of time suflicient to uniformly oxidize all of the fibers of the cellulose without excessive' loss of tensile strength after which the cellulose is subjected to a spinning process and after forming into threads is woven or knitted so as to form a fabric or knitted material therefrom. a

The cellulose in staple form, after it has been worked or .fiuffed so as to assure penetration of the N02 therein, may be treated either by gaseous N02, such as, described in U- S.'Patent No. 2,232,-

be carried out in the main 990 of Yackel and Kenyomwith a solution of N0 7 in a halogenated hydrocarbon such as described in Kenyon and Yackel application, Serial No. 571,012, filed January 1, 1945, or by immersing the cellulose in liquid N02 for a time. The time of fiber with the N02 is governed by the amount of carboxyl which it is desired to incorporate into the product. For instance, if the cellulose fiber is to be formed into a gauze which is to be employedfor bandaging or in external hemostasis it is only necessary that.

a carboxyl content on the order of -9% be imparted to the cellulose fiber. However if agauze is to be formed which is dissolvable in body fluids, thus being useful for'internal sponges and packings and also for external hemostasis, it is desirtreated for the desired length of time to impart the selected carboxyl content thereto it is washed and dried, then subjected to a spinning operation forming threads therefrom which threads are loosely woven into gauze.

.If desired, the staple cellulose fiber may be oxidized by gaseous N02 in which case the cellulose fiber may be subjected to a. stream of gaseous N02; for instance, for seven hours at a temperature not exceeding-60 C. such for instance, as within the range of to 25 C. The resulting oxidized cellulose staple, after blowing off the oxidizing gas, may be washed with distilled water The to completely remove the nitrogen oxide. product after air drying will be found to be completely soluble in dilute alkali such as v1% or 2%.

aqueous sodium hydroxide or in 0.15 molar sodium bicarbonate. A shorter time of treatment will impart less carboxyl content and alkali solube useful for surgical purposes with- ,tion resulting in a fabric, the nature of which debility may not be obtained. This material is then subjected to a spinning operation such as by employinga drawing operation to attenuate the fiber, followed by a twisting operation to form yarn or a thread therefrom. The yarn or thread is then subjected to a weaving 0r knitting operapends upon the looseness of the weaving or knitting operation.

If the cellulose fiber is to be oxidized by means of a solution of N02 in a halogenated hydrocarbon such as carbon tetrachloride, the fiber, after loosening, is placed in the solution of N02 in the 'body fluids and may for either external or internal wounds.

carbon tetrachloride, preferably at a temperature less than the boiling point of the N02, best at 20 C. or lower. If a substantial degree of oxidation is to be imparted, one may employ a,50% solution of nitrogen dioxide in halogenated hydrocarbon. However, the degree of oxidation also depends upon the time of contact of the fibers with the N02. The treatment may be from 1 to 16 hours but ordinarily 3 or 4 hours treatment of the fibers with this composition is sufficient to i give a product which has been oxidized to the point that it will be absorbable by body fluids. When the .oxidation'process has been run for the desired time, the oxidizing medium may be removed therefrom, such as by washing with alcohol and distilled water, and is then dried, such as at room temperature or a temperature which is slightly elevated, such as up to 50 C. The resuiting fibers are then subjected to drawing, spinning, and weaving, preferably to prepare a loosely woven fabric or gauze therefrom. The resulting gauze, particularly if a carboxyl. content of at least 13% has been imparted thereto is soluble in be employed as a dressing The accompanying drawings illustrate cotton gauze having suitable thread counts as are use ,ful in the described invention.

Figure l is a drawing of an oxidized cellulose gauze, the thread count of which is 20 x 12. Figure 2 illustrates a cotton gauze of oxidized celulose fibers, the thread able to prepare a product having a carboxyl conhas been 75, desired count of which is 20 x 20.

If desired, the cellulose fibers may be oxidized by means of immersion in 'liquid1N2O4 and allowing the mass to stand for several hours preferably 5m 10 hours, at a, temperature. not exceeding room temperature. The oxidizing material is then washed out and the fibers formed into a textile material. 7

By the above-described methods it is possible to prepare fabric of oxidized cellulose of any dimension without apprehension as to 1 80-85% of that of the. original cellulose.

desirable that the tensile strength of the oxidized shrinkage occurring, such as would change the condition, consisting substantially of cellulose and readily spun and woven. Nevertheless, it is to be understood thatother celluloses suitable for fabric formation maybe used as the starting material for preparing fabric in accordance with our invention, some of those which may be employed being jute, fiax, ramie, kapok, viscose and hemp. It is to be understood that wherever in the general description of this specification the treatment of cotton is described, one of these other fibers may be substituted therefor, the choice of the fiber to be used depending on all the circumstances involved. Where the oxidized fiber is to be used for surgical purposes, obviously the cellulose employed should be ina refined condition so as to avoid any impurities which might have detrimental physiological eflecta If the material to be oxidized is a. cellulose fiber having a considerably lower viscosity than native cotton or other native fiber, as for example some types of viscose fiber, the oxidation thereof with liquid or gaseous NO'z without diluent might reduce the tensile strength of the fiber to such an extent that difiiculty would be experienced spinning and weaving that material. In cases where a cellulose fiber having a low cuprammonium viscosity is employed as the starting material for oxidizing. and making fabric in accordance with our invention, we recommend that the oxidation be carried out by means of a solution of N204 in an inert solvent, such as carbon tetrachloride, as described and claimed in Kenyon and Yackel application, Serial No. 571,012.

We have found. that it is best in oxidizing cellulose staple with N02 to employ a proportion of N02 (or N204) amply suflicient to give the carboxyl content desired, con-trolling the obtaining of the desired carboxyl by the time of oxidation. By this means the loss of tensile strength upon oxidation is kept to a minimum. For instance, under these conditions the tensile strength of the oxidized cellulose may be approximately It is cellulose fibers be greater than 50% that of the original fibers, which is the case with oxidations not allowed to exceed approximately 16 hours.

Naturally, the purer the form of thereacting materials the better the product. Therefore, it is desirable to employ materials which are in a substantially pure form in order to obtain the best results. This alsofacilitates keeping the staple be employed which has been picked and carded or in other words from which stems and foreign matter have been removed and which has been disentangled and the fibers arranged in parallel order, such as to form a silver.

The fibers of the length ordinarily found in natural cotton (mostly Within the range of %2 /2 inches) are employed as the starting material for our invention, the criterion being that the fibers are of a sufficient length to be capable of spinning or forming into threads.

After the cotton has been oxidized to the desired degree, such as to a carboxyl content of 5%, 9%, 13%, 15%, or 18%, for example, it is converted into thread and then into fabric, particularlygauze fabric. A method of preparing thread from the staple cotton which has been found to be satisfactory is to first put the staple into a breaker in which operation it is fiuifed, followed by treatment in a carding machine so as to lay the cotton out into the form of a broad mat which is sent to the sliver for the formation of a card sliver, the cotton then being in the form resembling along, thick unbraided rope. The sliver is then put through the roving and spinning machines wherein it is twisted and drafted so as to form thread of the desired denier. The denier of the thread formed is adjusted by adjusting the amount of drawing, twisting, and

doubling to which the sliver is subjected, the

greater the degree of drawing and twisting the finer the thread which is obtained.

The thread is then wound in the form of cops or preferably as tubes or on spools, and for convenience each unit consists of 840 yards of thread. The thread count is the number of hanks of 840 yards which is required to make a pound of thread. It is desirable in operating in accordance nitrogen content down which is ordinarily desirable. When operating under the conditions specified herein, as illustrated by the examples, a

product having a nitrogen content from approxi-.

.l% to .5% will be obtained. The degree of oxidation obtained may range anywhere from 1% carboxyl up to the theoretical limit of 25% carboxyl by weight. This carboxyl is determined in terms of CO2 equivalence obtained by the uronic acid method described by Yackel and Kenyon in J. A. 0.8., vol. 64, pages 121 to 127 (1942).

The cellulose which is employed as the starting material in accordance with our invention should be in a condition whereby easy penetration of the oxidizing liquid occurs, thus insuring uniformity of oxidation. In the case of natural fibers it is therefore ordinarily desirable that with our invention that the threads be 20's, 30's or 40s as threads above 40's are rather fine for use in fabrics whereas threads below 20s are of more bulk than is desirable, particularly for surgical gauze or dressing.

After the thread has been formed it is woven into fabric by a weaving operation in which the thread to be employed as ends is drawn in, followed by the insertion of the picks therein by means of the shuttle to form the finished cloth. There is an advantage in using a greater number of threads per inch for the warp ends, particularly for surgical dressing material, as any tension applied to such material is ordinarily lengthwise thereof. A convenient material to prepare is one having a count of 20 ends per inch and 12 picks per inch using threads for ends having a count of 35 and those for fill having a count of 40. By this means a fabric which may be designated as a cheesecloth or gauze may be obtained having a weight of .6 ounce per square yard. In this way an open loosely woven fabric is obtained. If desired, the warp threads may be employed by pairs and one of these threads may be made to crossthe other at every pick to the right and to the left alternately, thus avoiding sliding of the picks'over the warp threads.

The number of warp ends and picks per inch may be varied as desired by the individual operator. For loosely woven fabrics it would ordinarily be desirable to stay within the range of 15 to 40 ends and 10 to 40 picks per inch. If desired, the fabric may have the same number of ends and of picks per inch. For instance, a fabric may be conveniently prepared having 25 ends and 25 picks per inch using a 20 count oxidized cotton thread for both; the resulting material is then ready for use directly for surgical packing after sterilization, such as with alcohol, formaldehyde, or some other disinfecting material. The following examples illustrate our invention:

Example 1.-450 part of a long-fibered staple cotton'were added to a solution consisting of 2700 parts by weight of liquid N20. and 5400 parts by weight of carbon tetrachloride. The cotton was held below the surface of the liquid and was maintained at room temperature for 16 hours. At the end of this period the cotton was drained free of the oxidizing liquor, rinsed in fresh carbon tetrachloride, and then subjected to a current of air to remove the excess of carbon tetrachloride and any nitrogen oxide gases which might be present. The oxidized cotton was then washed with distilled water until the washings were acid free. The product was centrifuged and air dried at room temperature. Uronic acid analysis indicated this product to have a carboxyl content of 15.1%. The nitrogen content was 0.3% and the resulting material was found to be completely and readily soluble in 1% sodium hydroxide.

The oxidized cotton obtained was fluffed in a breaker, put through a carding machine so as to lay out in the form of a broad mat, slivered, and then sent through roving and spinning machines to twist and draft the sliver, the thread obtained having a count of 35. Another portion of the oxidized cellulose was put through the same operations, only the amount of drawing in the operation was increased so that a thread having a higher count is obtained. In this case the thread obtained was found to have a count of 41.6 which may be termed for practical purposes as a count of 40. The latter threads were used for the picks in the weaving operation, and the threads having the 35 count were used for the warp ends.

The oxidized cotton thread was then woven using the count 35 thread for the warp ends and the count 40 thread for the picks, a cloth being prepared having 20 ends and 12 picks per inch. The cloth obtained is a loosely woven material ideally suitable for surgical gauze, cheesecloth, or mosquito netting. For surgical gauze purposes the cloth so formed is woundinto rolls, such as having a width of 12 or 18 inches subjected to formaldehyde sterilization. The material thus obtained, when properly sterilized, is eminently suitable for use in packing for wounds or for surgical dressings, particularly where bloody conditions obtain. This material is suitable both for internal and external surgery as it will dissolve within the body and thus maybe win conditions where it is desirable to leave packing in. a wound which is closed up.

Example Zr-Six parts of staple cotton containing 4 to 6% moisture was mixed with a solution of 36 parts by weight of liquid N204. in 36 parts by weight of carbon tetrachloride. After standing at room temperature for 1 /2 hours the mas was pressed to squeeze as much oxidizing liquid as could be removed in this manner, whereupon the product was then blown with air, washed and dried as in the preceding example. The material did not dissolve in 1% sodium hydroxide solution. Uronic acid analysis indicated the product had a carboxyl content of 7.2%. A Devarda nitrogen determination of 0.23% was obtained.

The resulting oxidized cotton was fluiied in a breaker, put through a carding machine to form a broad mat from the cotton, then put through a sliver to form a long, thick card sliver, and

then through the roving and spinning machines, whereupon thread of approximately 30 count was formed. This thread was used to form a loosely woven fabric using it for both the ends and the picks of the fabric. A fabric was woven in which both the ends and the picks were 20 to the inch. This fabric of oxidized cotton, after sterilization was useful for a dressing for wounds, cuts, or burns where the dressing was to be removed after a time as this fabric is not soluble in body fluids, at least within a reasonable period of time. However, it gelatinizes and is readily separable from the body tissues. When this gauze is applied to tissues, even though bleeding is present it may be removed therefrom at any time desired without sticking of the gauze fabric to the body tissues occurring.

Example 3.-Five and one-half parts of long fiber cotton were immersed in a solution consisting pf 36 parts by weight of liquid N204 in 36 parts by weight of cyclohexane. The vessel was loosely closed and allowed to stand for 16 hours at room temperature. At the end of this period the excess oxidizin liquid was removed from the cotton and the product was washed and dried as in Example 1. The oxidized cotton obtained was completely soluble in 1% sodium hydroxide solution and contained 20.2% of carboxyl determined by the uronic acid method. The nitrogen content was determined to be 0.4%

The resulting cotton was formed into thread and then made into a fabric having 20 ends and 12 picks per inch. The resulting loosely woven fabric which may be termed cheesecloth or surgical gauze after sterilization is suitable for use either internally or externally as this material is soluble in body fluids. 7

Example 4.-Fifty .parts of well-fluffed, longfiber cotton were placed in a closed vessel and a slow stream of gaseous N204 at room temperature was introduced into the bottom of the vessel, thus filling it. A gas exit was provided at the top. The slow stream of gaseous N02 was maintained thus for 6 hours. At the end of this period excess gas was blown out and the oxidized cotton was washed with distilled water until the washings were acid free. The product was completely soluble in 1% sodium hydroxide solution. Uronic acid analysis indicated it to have a car'- boxyl content of 13.9%. The resulting oxidized cotton was put through the operations specified in Example 1 and a fabric of the same thread count and number of ends and picks per inch was obtained. The loosely woven fabric obtained was suitable after sterilization for surgical purposes.

This material was soluble in body fluids and, therefore, could be employed for internal dressings as well as external applications.

Example 5.-Ten parts of purified ramie fibers were placed in the flask portion of an apparatus, such as illustrated by Fig. 2 of Yackel and Kenyon, Patent No. 2,232,990, and the system was evacuated. Ten parts of liquid N02 were drawn into the system in such a manner that liquid N02 did not come in contact with the fibers. This system was then allowed to stand at room temperature for sixteen hours. The product was then removed from the apparatus, washed with distilled water until the washings were acid free, and then air dried at room temperature. The resulting product upon analysis was found to have a carboxyl content of 21.8% and a nitrogen content of 0.24%. The resulting product was formed into fabric as described in the previous examples.

Example 6.-Ten parts of viscose yarn ates r07 denier and 40 filaments were immersed in 'a' solution of 60 parts of liquid N204 and 120 parts oi carbon tetrachloride, the parts in each case being parts by weight. The vessel containing the mass was stoppered lightly and let stand at room temperature. After sixteen hours the yarn was separated from the liquid, rinsed with fresh carbon tetrachloride and then washed with distilled water until the washings were acid free. The yarn was then dried at room temperature. The carboxyl content was found to be 23.4%. The oxidized yarn was woven into fabric.

Example 7.Ten parts of purified ramie yarn were placed in a vessel and covered with a solution consisting of 62 parts of N204 and 124 parts of carbon tetrachloride. The mass was allowed to stand for sixteen hours and the fiber was then removed, washed and dried as in the preceding examples. A yarn was obtained suitable for spinning and weaving into fabric. The resulting product had a carboxyl content of approximately 18%.

Example 8.-One-half part'of flax fiber was placed in a vessel and covered with a solution of 3 parts of N204 and-6 parts of carbon tetrachloride. The vessel was stoppered lightly and allowed to stand at room temperature for sixteen hours. The resultin fibers were suitable for forming into fabric. These fibers had a carboxyl content of approximately 22%.

In making fabric in accordance with our invention the ends and picks per inch will ordinarily be governed by the count of the thread which is employed in making the fabric. For instance, with a thread count of 20, it will not be necessary to employ the number of ends and picks per inch to obtain a given tensile strength that it would be ifthread of a count 40 is used. As a matter of fact, with the use of heavier thread it is desirable to use a less number of ends and picks to assure the obtaining of a fairly light weight fabric. This same idea holds true in cases where the gauze which is woven uses pairs of threads for the warp ends in its preparation, the necessity for the number of these pairs per inch being half of that desirable when single threads of the same count are used.

We claim:

1. Surgical fabric consisting of Woven threads of uniformly oxidized cellulose fibers.

2. Surgical fabric consisting of woven threads of uniformly oxidized cellulose fibers having a carboxyl content of 13-20%.

3. Surgical fabric consisting of woven threads of uniformly oxidized cellulose fibers having a carboxyl content of 5-9.%.

4. Surgical gauze consisting of loosely woven threads of uniformly oxidized cotton.

5. Surgical gauze consisting of loosely woven threads of uniformly oxidized cotton having a carboxyl content of 13-20%.

6. Surgical gauze consisting of loosely woven threads of uniformly oxidized cotton having a carboxyl content of 5-9%.

- WILLIAM O. KENYON. CORNELIUS C. UNRUH.

REFERENCES CITED The following references are of record in the file of this patent: 

